1. Field of the Invention
The present invention relates to an array substrate, a liquid crystal display (LCD) panel having the array substrate and an LCD device having the LCD panel. More particularly, the present invention relates to an array substrate with enhanced display quality, an LCD panel having the array substrate and an LCD device having the LCD panel.
2. Discussion of the Background
Generally, various electronic devices such as monitors, notebook computers, television sets, cellular phones, etc., are required to be thin and lightweight. Hence, various flat panel display devices, which have better characteristics than conventional cathode ray tubes (CRT), have been developed.
A liquid crystal display (LCD) device displays an image using optical and electrical properties of liquid crystals. The LCD device has advantageous characteristics such as it may be made lightweight, and it has relatively low power consumption and driving voltage.
Since LCD devices have been widely applied to various information-processing devices, such as, for example, notebook computers, computer monitors, television sets, and cellular phones, the need for improved display quality has increased.
The LCD device includes an LCD panel, which includes an array substrate, an opposite substrate, and a liquid crystal layer interposed between the array substrate and the opposite substrate. The array substrate includes a plurality of data lines and a plurality of gate lines that cross each other and define a plurality of pixels.
Each pixel includes a switching element, a liquid crystal (LC) capacitor, and a storage capacitor. A first electrode of the LC capacitor may be a pixel electrode that is electrically connected to a drain electrode of the switching element, and a second electrode of the LC capacitor may be a common electrode that is formed on the opposite substrate. A first electrode of the storage capacitor may be the pixel electrode, and a second electrode of the storage capacitor may be a common electrode that is formed on the array substrate.
When the gate signal that is applied to a gate line is applied to a gate electrode of the switching element, the switching element turns on. Then, the data signal that is applied to a data line is applied to the pixel electrode through the source electrode of the switching element.
Moreover, after applying the data signal to the pixel electrode, which is the first electrode of the storage capacitor and the first electrode of the LC capacitor, a uniform DC voltage may be applied to the second electrode of the storage capacitor in order to maintain a voltage level of the data signal. Therefore, charges corresponding to the data signal may be charged in the LC capacitor and the storage capacitor so that liquid crystals vary their arrangement in response to an electric field formed by the charges. Thus, an image is displayed using transmitted or reflected light through the liquid crystals.
However, the storage voltage line of the storage capacitor is electrically connected to the common voltage line in a first direction, and it is overlapped with the pixel electrode. Moreover, the second electrode of the storage capacitor, which is the common electrode of the array substrate, receives a common voltage from an external device through a common voltage line that is formed on the LCD panel in the second direction.
Therefore, the common voltage is applied to two end portions of the LCD panel through the common voltage line, and currents applied to various positions of the LCD panel may differ from each other due to an RC delay of the storage voltage line.
Accordingly, when a coupling defect is formed between the pixel electrode and the common electrode of the array substrate, a common voltage may be distorted at the end portions and a central portion of the LCD panel, thereby displaying a greenish image on the central portion of the LCD panel and deteriorating the LCD panel's image display quality.